Hydrodynamic radius dictates sensitivity of x-ray detectors based on the radiomicrofluidic synthesis of colloidal silver.

A radiolytic synthesis of silver nanoparticles was carried out in combination with a microfluidic method to produce liquid radiation detectors. The detector response was analyzed by correlating the absorbed dose with the dispersion's absorbance and with the hydrodynamic radius (HR). Samples were irradiated with x-rays of varying beam energies and dose rates and the data were discussed to elucidate how nucleation and growth processes are affected by the radiation quantities. Results reveal that HR does not change with the absorbed dose, but can be well controlled by varying the precursors concentration, beam energy, and dose rate. Increased precursor concentrations or dose rates favor nucleation, leading to the formation of smaller HR particles and increased detector sensitivity. Upon increasing the x-ray energy, growth is favored, leading to larger HR and decreased detector sensitivity. It is shown that HR and detector sensitivity are strongly correlated so that HR dictates detection sensitivity: the smaller the HR, the higher the sensitivity. Therefore, the dependence of the HR on the dose rate and on the x-ray energy establishes a new method for the controlled growth of colloidal silver, besides opening new possibilities for ionizing radiation detection.